Yes,  and it isn't nice to fool with Mother Nature.  I got nailed
between finger and elbow at 25KV from a huge capacitor bank supplying
a hydrogen thyratron switch tube - OWWWW.  I was reaching into the
wire cage and shame on me, I didn't have the ground strap on the bus.
I knew better .001 second later.

Oh, and having a screwdriver in your hand in the vicinity of the neck
of a CRT is another no-no.  The anode and the glass envelope is quite
a nice Leyden jar!  Those CRTs stay charged up a long time, esp. the
big old metal jacketed color tubes.

My hand was numb for quite a while on that one.

ICs are for wimps!

Bob

----- Original Message -----
From: Scott Decker <[log in to unmask]>
To: <[log in to unmask]>
Sent: December 15, 1999 12:03 PM
Subject: Re: [DC] PWB High Voltage Material Choices?


: Why Bob,
:    It sounds like you have had the unfortunate discomfort of that
nasty HV
: stuff too... Ah yes, the old one hand in the pocket thing. I do
remember it
: well. Your words are well taken about the High Altitude part also. I
worked
: with a customer that needed a light fixture in a large cable drum,
(cable
: was a mile long LF antenna) and as it turned out they almost didn't
need to
: power the light. The corona around the fixture was so bad AND
bright, the
: comment was, "we don't need no ..... power to the light". Anyway, I
just
: wanted to make these comments that as most of you may have guessed,
don't
: have a lot to do with the subject, I just had to type something on
the
: keyboard. :-)   <G>
: Have a good holiday everyone...
:
:         Regards,
:         Scott Decker
:
:         AKA: PadMasterson
:         Mentor Design Supervisor, Portland
:         7245 NW Evergreen Pkwy., Suite 100, Hillsboro OR 97124
:         (503)531-2050 ext. 1820 FAX: (503)531-2051
:         [log in to unmask] <mailto:[log in to unmask]>
: <mailto:[log in to unmask] <mailto:[log in to unmask]> >
:          Tyco Design
:         Formerly Praegitzer Design, The Fine Line in Printed
Circuits
:
:
:
:         -----Original Message-----
:         From:   Bob Landman [SMTP:[log in to unmask]]
:         Sent:   Wednesday, December 15, 1999 8:28 AM
:         To:     [log in to unmask]
:         Subject:        Re: [DC] PWB High Voltage Material Choices?
:
:         Greg,
:
:         One item you need to know is the maximum working altitude.
At low
: air
:         pressure, arcing and corona are a serious problem. 30KV is
certainly
:         going to produce corona if there are any sharp points.
Conformal
:         coatings help - make sure the material can withstand the HV
and
: ozone
:         production without degrading significantly.
:
:         You have to assume that dirt is attracted to the board due
to static
:         field effects.  The conformal coating makes sure that the
dirt can't
:         short out the board.  Look inside any TV monitor and you
will see
: that
:         they are filthy after a few months of operation but they
keep on
:         working.  That's good design.  Also, assume that this dirt
reduces
:         heat being shed by the parts (forced or natural convection
effects
: are
:         reduced as dirt is not a good heat conductor.
:
:         Just be as conservative in your design as $$$ will allow.
(and keep
:         your fingers away and my favorite rule around HV is that I
always
: keep
:         one hand in my pocket at all times [across the chest HV is
deadly
:         stuff!)
:
:         Bob
:
:         ----- Original Message -----
:         From: Greg Kaskey <[log in to unmask]>
:         To: <[log in to unmask]>
:         Sent: December 15, 1999 10:07 AM
:         Subject: [DC] PWB High Voltage Material Choices?
:
:
:         All,
:
:         I hope you are doing well.
:
:         What PWB Material do I call out for one that is 0.074 inch
thick and
:         it does
:         High Voltage Multiplying with 30K Volt Output?
:
:         The board has no solder mask and is encapsulated in a
"Black, Rubber
:         Like
:         Material".  Also, the Board looks like it has some kind of
clear
:         coating that
:         does not remind me of a "normal" protective coating which is
applied
:         to the
:         entire finished assembly; it is soft vs. hard and can be
easily
:         scraped off.
:
:         What questions would I need to ask to determine some of the
material
:         choices?
:
:         Thanks for Helping,
:
:         Greg Kaskey
:         Sector Electronics, Inc.
:         V: 770-955-8044
:         E: [log in to unmask]
:
:
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